Slit chillies without cutting through.
Put gram flour, salt, red chilli powder and yogurt in a bowl and whisk well. Add turmeric powder and whisk again. Add 1 cup water and whisk well.
Heat butter in a non-stick pan. Add rice, salt, mixed herbs and mix well. Let it get heated through.
Place fish pieces on a plate. Put salt, 1 tsp lemon juice and ginger-garlic paste on them and rub well on both sides. Set aside to marinate for 10-15 minutes.
Transfer the herb rice onto a serving dish and spread to make a bed.
Take 2 satay sticks and insert 2 chillies and 2 marinated fish pieces alternately onto each of the sticks.
To make sauce, heat 1 tsp oil in another non-stick pan, add mustard seeds and let them splutter. Add yogurt mixture and cook till it thickens.
Heat some oil in a non-stick grill pan. Place the prepared fish and chilli sticks on it, spread the left-over marinade on top and grill, turning sides, till evenly done on both sides.
Add remaining lemon juice to the sauce and mix well and cook for a minute.
Place the grilled sticks on the rice, pour the sauce over and serve hot.